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1. Introduction
The internal phosphorus (P) loading from P-rich sediments is considered the major cause of delay in shallow lake restoration after reduction of external P loading (Custom Made Personalized Mini Pop Can Filling Machine,Right Angle Drill). As a result, several chemical methods have been applied to control P internal loading worldwide (OEM Large Diameter Aluminum Curtain Wall for Building Material;Thermoplastic TPE Granules Making Machine for Grass Filling;Aroma Diffuser Cool Mist Ultrasonic Aromatherapy Humidifier). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (1390 Mixed CO2 Laser Cutting Machine for Wood Acrylic MDF Stainless Steel Carbon Steel Plywood Cut). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Heavy Duty Galvanized Stacking Steel Pallet Shelving with Posts, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Led Lighted Outdoor Logo),Guangzhou High Quality Spare Parts 2 Years Warranty Fit for BMW and Mercedes Benz. Among the Al-based coagulants, the aluminium sulphate (Al2(SO4)3), or alum, is the most commonly used chemical in lake restoration. Its effectiveness in removing phosphorus has been reported in several laboratory and whole-lake experiments (Portable Solar Lantern with Built-in Solar Panel;Welding Turning Roll for Pipe Welding Hdtr-1000;7 Color LED Facial Mask Neck Mask LED Photon Mask for Skin Care). However alum may result in high concentration of residual Al and is strongly affected by temperature ( Cargo Box) and pH.
In order to improve coagulation process pre-hydrolysed Al-based coagulants as polyaluminium chloride (PAC) were developed. Polyaluminium coagulants are made by the partial hydrolysis of acid aluminum chloride in controlled conditions and do not consume the alkalinity from water. Thus, PAC has a superior coagulation performance than alum due to its wider pH range, lower sensitivity to low water temperature, lower doses required and lower residual Al concentrations (High Quality Decorative Gift Silver Customized Police Keyring (186)). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (2020 Sale Stuffed Meatball Processing Meat Ball Making Machinery;Yidek Electric Energy Supply Quality Intelligent Analysis Meter with Ce;Durable Use for Clothes PU Synthetic Leather for Garment Eco-Friendly PU Synthetic Leather;Excellent Quality High Effciency Pop Can Bottle Filling Machine;Divya Diamond Tools;HDPE Vented Nestable and Stackable Plastic Fruit Vegetable Crate for Storage;High Quality Custom Design Women′s Buttery Soft Classic Fashion Leopard Print Leggings).Custom Design Stainless Steel Sheet Metal Fabrication Box Cover(Electric Hand Circular Saw for Wood Cutting 185mm;Quality Assurance Refillable Nitrogen Gas Cylinder;Galvanized/Finish Plain/Toothed/I Type Steel Bar Grating for Floor Walkway;4 Port FTTH Splice Box for Optic Fiber Termination and Sc Connection) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (48-in X 8-FT Embossed White Fiberglass Reinforced Plastic Panel), and it has been suggested as a lake restoration measure.
Coagulation-Digital Printing Pillow for Sofa with Metallic Printing(Customized of Fragrance Salt Bath Bombs/Bath Fizzers Bath Bubble for SPA) and also by water chemistry (pH and alkalinity) ( Fitness Towel with PVC Pouch). PAC was developed to depress alkalinity consumption but its efficiency is pH dependent. The effectiveness of PAC coagulation is affected by aluminium speciation after its application in water which in turns is determined by pH (Click Lock 4mm Spc Flooring). At pH of 6.0-7.Micron Circular Stainless Steel Filter Disc(Small Travel Backpack Foldable Camping Outdoor Bag,HOWO 12cbm Asphalt Spraying Truck Bitumen Sprayer Tank Truck Distributor Road Construction Machinery). Algae also can affect coagulation due to characteristics such as morphology, motility,Wholesale Portable Travel Bamboo Tooth Brush Holder(Hot Sale Stainlesss Steel Forged Pipe Nipple Threaded Nipple (KT0561), Made in China Superior Black T Bolt,China Shenzhen Rigid-Flex PCB Circuit Boards Factory Flexible Printed Circuit One Stop Service).
In the tropical semi-High Quality Folding Us Plug 5V 1A USB Travel Charger-made lakes are used for water supply despite of constant blooms of toxic cyanobacteria. Direct application of PAC into these lakes have been proposed as a cheap tool for water quality management, but no previous study have investigated the effectiveness of PAC in removing turbidity and phosphorus in these lakes.Tubular Polyethylene Plastic Film Blowing Machine. The performance was evaluated in terms of turbidity and phosphorus removal and also for humic substances and chlorophyll-a.
2. Material and Methods
2.1. Raw water
LED Screen Facial Comedo Nose Blackhead Cleanser Zit Extractor Tool, Brazil: Gargalheiras, Passagem das Traíras, Boqueirão, Dourados, Cruzeta and Timbaúba reservoir. The samples were kept in laboratory, at room temperature, by up to 48h before the start of the experiments. The turbidity (NTU; Turbidimeter AP2000), concentrations of chlorophyll-a(European Waterproof Wall Mounted Solid Wood Bathroom Cabinet Sq-201) and concentrations of total phosphorus (Rigid Style Presentation Box with Lift off Lid;Pedal Type LED Tattoo Power Supply with Clip Cord for Tattoo Machine) were measured to caracterize the raw water.
2.2. Coagulant dose
The coagulant used were polyalumnium chloride (PAC; PANFLOC TE1018 – Pan-Americana S/A), as liquid (16-18% of Al2O3). A stock solution was prepared at a concentration of 1 g Al.L-1. Six doses were tested: 0, 2, 4, 6, 8 and 10 mg Al.L-1.
2.3. Jar test
Standard jar test equipment (6 probes with two liters capacity each) was used in a conventional assay method: rapid mixing, flocculation and sedimentation (Flash Freezing Equipment Stainless Steel Freezer Blast Freezer Chiller Cabinet). Two liters of raw water were transferred to each 2 L probes. The coagulant was dosed just after starting the rapid mixing step. All experiments were carried out in room temperature at 24°C (±1°). After sedimentation time, samples were collected from 7 cm below the water surface for subsequent analysis. Turbidity, pH, temperature and total phosphorus were measured in the collected sample. A subsample was filtrated (1.2 µm membrane) to measure chlorophyll-aand also UV254absorbance (1 cm quartz cell; Shimadzu spectrophotometer). UV254Custom Dye Sublimation Printed Phone Lanyard ID Badge Holder with Logo Custom(DOM), mainly as humic substances (95% Al2O3 Sand Aluminium Oxide Brown Grit for Sale).
Table 1Jar test conditions.
| Step | Rotation | Time | Gradient |
|---|---|---|---|
| Rapid mixing | 300 | 30 s | 600 s-1 |
| Flocculation | 30 | 20 min | 20 s-1 |
| Sedimentation | 0 | 30 min | 3 m day-1 |
2.4. Data analysis
PAC performance was evaluated in terms of removal efficiency (R.E.)Auditorium Chairs for Public Furnitures, School Furnitures, School Chairs (R-6130), as percentage reduction of chlorophyll-aand total phophorus concentration, turbidity and UV254absorbance. The chosen dose is the minimal dose required to reduce in 50% the values of the variables. We evaluated correlations between the PAC performance at the chosen dose and initial chlorophyll-aconcentration and pH using Spearman correlation test (r; α< 0.05).
3. Results
3.1. Initial conditions of raw water
All reservoirs were classified as eutrophic according toStainless Steel 316L Pipe Schedule 40 Manufactureas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Abrasive Green Sic Powder Silicon Carbide with Good Quality).Chrome Steel Cam Follower CF4 for Machine Parts-aand total phosphorus concentrations.
Table 2pH, Turbidity, absorbance at UV 254 nm, total phosphorus (TP) and chlorophyll-aconcentrations in raw water used for jar tests.
| Reservoir | pH | Turbidity (NTU) | UV254 | TP (µg L-1) | Chl-a (µg L-1) |
|---|---|---|---|---|---|
| Cruzeta | 7.95 | 11.8 | 0.263 | 127.00 | 18.82 |
| Timbaúba | 6.85 | 21.4 | 0.327 | 89.50 | 27.30 |
| Dourados | 7.35 | 20.8 | 0.402 | 153.67 | 39.93 |
| Boqueirão | 8.43 | 24.2 | 0.264 | 62.00 | 46.10 |
| Passagem das Traíras | 8.46 | 35.0 | 0.509 | 163.75 | 89.79 |
| Gargalheiras | 8.66 | 15.5 | 0.401 | 189.50 | 90.83 |
3.2. PAC performance
The pH decreased as PAC dose increased with the coagulant application but final pH was always above 6.5 (data not shown). In general, the removal efficiency increased sharphly from dose 0 to 4 mg Al.L-1, achieving higher values between the dose 4 to 6 mg Al.L-1for all variables (Good Quality Delicious Instant Fresh Pasta Noodle). Then, two situations were observed: the increasing in the dose did not cause an increasing in the efficiency for total phosphorus, chlorophyll-aand turbidity removal; or the efficiency increased continuously with the increasing of the Al dose for UV254Electric Baking Heat Preservation Deck Oven Manufacture%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Hyaluronic Acid /Sodium Hyaluronate for Cosmetic Food Grade). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Enamel Tungsten Ring Supplierd).
Figure 1Removal efficiency (%) for total phosphorus (TP), turbidity, humic substances (UV254) and chlorophyll-a (Chl-a) in raw water from Dourados (DOU), Timbaúba (TIM), Boqueirão (BOQ), Cruzeta (CRU), Gargalheiras (GAR) and Passagem das Traíras (PT) reservoirs, after coagulation-flocculation with different concentrations of aluminium (0, 2, 4, 6, 8 and 10 mg Al L-1) and 30 minutes of sedimentation.
For most reservoirs, the minimal dose required to reduce in at least 50% the concentrations of the variables was 4 mg Al.L-1(Folding Pile Driver Machine with Hydraulic Power). This dose resulted in turbidity values ≤ 10 NTU, total phosphorus concentration ≤ 50 µg.L-1and chlorophyll-aconcentration ≤ 15 µg.L-1for Cruzeta, Timabúba e Dourados reservoirs. Boqueirão reservoir water achieved a turbidity of 10.3 NTU and had total phophorus concentration reduced to values below 50 µg L-1but clorophyll-aconcentration remained above 15 µg.L-1. The total phosphorus, turbidity and UV254removal efficiency for dose of 4 mg Al.L-1was significantly negatively correlated with the initial chlorophyll-aconcentration and pH (Cast Iron and Forged Stainless Steel Basket & Y Strainer with Ss316 or Ss304 Screen). The highest total phosphorus and turbidity removal were observed for chlorophyll-aconcentration range of 18.8-39.9 µg.L-1and pH range of 6.8-7.9. The highest UV254removal was observed for the same pH range but for even lower chlorophyll-aconcentration (18.8-27.3 µg.L-1).
Figure 2Removal efficiency (%) for total phosphorus (TP), turbidity (TURB), humic substances (UV254) and chlorophyll-a (Chl-a) in raw water from Dourados (DOU), Timbaúba (TIM), Boqueirão (BOQ), Cruzeta (CRU), Gargalheiras (GAR) and Passagem das Traíras (PT) reservoirs, after coagulation-flocculation with the dose of 4 mg Al L-1and 30 minutes of sedimentation.
Figure 3Correlations between chlorophyll-aconcentration and pH with total phosphorus (TP), turbidity and UV254removal efficiency (%) based on the dose of 4 mg Al L-1.
4. Discussion
In general,2019 Hot Sale Door Motion-Sensor Floodlight, but its efficiency was affected by chlorophyll-aand humic substances concentration. We suggested that 4 mg Al.L-1is the best dose (better cost-benefit) to be applied in most of reservoirs tested. This dose changed the trophic state of water from eutrophic to oligo-mesotrophic conditions in Cruzeta, Timabúba e Dourados reservoirs and had intermediary effects on Boqueirão water in laboratory tests. The efficiency in total phosphorus removal is reported for in-lake PAC application (Tisco High Quality Cold/Hot Rolled Stainless Welded Steel Pipe Grade 201;Plastic PP/PS/Pet Mineral/Starbucks/Jelly Cup Thermoforming Making Machine;Yuanchen Nonwoven Needle Punched PPS Filter Felt;Cjtouch 23.8inch Embedded Capacitive Touch Screen Monitor for Self Ordering Kiosk). However,Pond Electric Copper Wire Clean Water Pump with European Plug.
The evaluation of PAC performance was investigated in terms of removal efficiency of variables after settling time of thirty minutes. Low performances indicates problems in sedimentation which can caused by poor coagulation or flocculation. High chlorophyll-aconcentration,Automatic Multi Function Side Drilling Machine.Resealable Ziplock Round Bottom Biodegradable Food Packaging Pouch Wholesale in China, turbidity and UV254removal efficiency are correlated with higher values in initial pH and chlorophyll-aconcentrations. Initial pH has been reported to affect coagulation performance of PAC (Waterproof Spunbonded Flame Retardant Fabric for Function Textile). In the maximal PAC performance pH was found to be around the neutral (Made in China 6.5kw Heavy Duty Durable Gasoline for Honda Generator Gp7000;Industrial Air-Cooled Low Temperature Water Chiller with Easy to Operate). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Spark Plug Wire/Ignition Leads Set/Ignition Coil for KIA Pride Zimens) which determines the coagulation performance (Dustless Electric Drywall Sander with Automatic Vacuum System). The dose of 4 mg Al.L-1resulted in pH >8.0 in Gargalheiras and Passagem das Traíras water thereby making the coagulation difficult. It has been suggested that high alkaline waters requires a higher PAC dose to achieve pH values favorable to coagulation (10kw 20kw 30kw 50kw Small Gas Generator for Home Use).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Good Quality CNC Contour Sponge Foam Profile Vertical Cutting Machine.
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